Volunteers from TVPS are planning events for World Aids Day
A Berkshire HIV and Aids charity has experienced a "significant rise" in referrals from women in their 30s and 40s in Slough and Reading.
Thames Valley Positive Support (TVPS) works in both towns, designated HIV hotspots by the Department of Health.
TVPS was set up 25 years ago, and supports over 500 people with HIV and or Aids, taking on average two new referrals a week.
The TVPS director said single women in their 30s and 40s were at risk.
Sarah Macadam, director at the HIV charity, said newly divorced or separated older women were not thinking about safe sex or using protection when meeting new partners.
"These are women who are perhaps lacking in confidence anyway and have just come out of a difficult relationship, and just aren't comfortable asking anybody they meet to use protection," she said.
"We had a woman quite recently who was diagnosed positive and has just found out she's going to be a grandmother.
"She just can't get her head round how she's going to tell her granddaughter or her daughter."
A woman who uses the centre, told BBC Radio Berkshire reporter Maggie Philbin how she felt when she learned she was HIV-positive.
"I didn't believe it. I said: "Oh God, why me?" I was crying and crying and crying," she said.
The TVPS charity started in 1985 as a support group organised by HIV-positive people in the area.
The group would meet and talk about their experience at each other's houses.
Referrals to the charity have grown in the past five years, an increase TVPS puts down to two factors: the charity's higher profile, but also the population increase and migration in the area from areas such as Poland and Africa.
About 50% of clients using the charity are from overseas, a consequence of Slough's proximity to Heathrow according to TVPS director Sarah Macadam.
HIV infections in the UK are still on the rise, but the charity reports that the virus continues to be surrounded by stigma.
Ms Macadam said: "Our centre is a safe haven for people to be able to come and talk openly and honestly about HIV without fear of being discriminated against.
"We also work hard raising awareness and try to educate the community, as to combat stigma, we feel knowledge is the key."
A user of the centre, who asked to remain anonymous, told presenter Maggie Philbin how it felt to be diagnosed HIV-positive.
"It was three years ago in November that I was diagnosed," he said. "I was at the Royal Berkshire Hospital.
"It's a numb feeling. You feel "no I can't be, they must be wrong".
"I was sort of expecting it but it still comes as a shock. It's like hitting a brick wall, that's the only way I can describe what it is and it's not a nice feeling at all.
"As much as people told me "you're not going to die", there's always that feeling, you are going to die, what does my future hold, how long have I got to live, what are my prospects?
"You read up on the internet, the internet is very frightening. It was like, where do I go from here?
"At the same time I was diagnosed I was suspended from work about my sexuality.
"I didn't come to the centre straight away because I didn't know about the centre when I was first diagnosed.
"It was lovely finding out about the drop in centres and being able to talk.
"If you want to talk about your HIV you can, but the team is great, the door is always open, even if you just want to come in for a cup of coffee."
To mark World Aids Day on 1 December, TVPS is organising a number of events to promote safe sex.
A World Aids Day walk from Slough town hall will take place at 1130 GMT on Wednesday 1 December, arriving at Windsor Leisure Centre at 1330 GMT.
In Reading, TVPS will hand out information at the Civic Centre to raise awareness surrounding HIV.
On Friday 3 December the charity will be offering free condoms and sexual health advice at Bar Soko from 2100 GMT to 0100GMT.